1. Field of the Invention
The present invention relates to a zoom lens and an image capture apparatus, and particularly to a zoom lens which is suitable for an interchangeable lens releasably attached to a silver-salt-film single-lens reflex camera or a digital single-lens reflex camera, being high-performance and ensuring sufficient lens back focus, and to an image capture apparatus using such a zoom lens.
2. Description of Related Art
In recent years, as the number of pixels in photoelectric conversion devices increases, there are demands for higher-performance image-taking optical systems, and moreover, for zoom lenses with small F-numbers covering a wide-angle range. In addition, in interchangeable lenses, there is a restriction that sufficient lens back focus be ensured, and this leads to difficulties in, e.g., correcting distortion associated with their wider-angle implementations.
In a related art, e.g., Japanese Patent Application Publication No. JP 2004-198529 (Patent Literature 1) proposes a zoom lens having an F-number at a wide-angle end of 2.8, with a six-group zooming configuration including, in the following order from an object side, a negative first lens group, a positive second lens group, a negative third lens group, a positive fourth lens group, a negative fifth lens group, and a positive sixth lens group.
In addition, Japanese Patent Application Publication No. JP 2004-101739 (Patent Literature 2) proposes a zoom lens whose F-number is in the order of 2.9 in the entire zooming range, with a four-group configuration, in which a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group are arranged in order of mention from the object side, and all the lens groups move independently of one another during power variation.